| 1. |
- Dan, Lilin, et al.
(författare)
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Design of Offset Spatial Modulation OFDM
- 2021
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Ingår i: IEEE Transactions on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0090-6778 .- 1558-0857. ; 69:9, s. 6267-6280
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the idea of offset spatial modulation (OSM) is integrated with orthogonal frequency division multiplexing (OFDM), toward an efficient design to bridge their advantages. Compared to its conventional counterpart as spatial modulation (SM)-OFDM, the proposed OSM-OFDM scheme aims at providing a simplified implementation structure with less number of radio frequency (RF) chains, by introducing an offset between the RF chain and the index of the activated transmit antenna on each subcarrier. Specifically, three types of offset antenna selection (OAS) methods are developed to meet different scene requirements for different number of available RF chains. Furthermore, through theoretical analysis, we quantify the bit error rate upper bounds of OSM-OFDM with different types of OAS methods. Finally, extensive computer simulations demonstrate that OSM-OFDM provides a flexible tradeoff among implementation cost, computation complexity and error performance.
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| 2. |
- Niu, Hong, et al.
(författare)
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On the Efficient Design of RIS-Assisted Secure MISO Transmission
- 2022
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Ingår i: IEEE Wireless Communications Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 2162-2337 .- 2162-2345. ; 11:8, s. 1664-1668
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Tidskriftsartikel (refereegranskat)abstract
- For the sake of improving the physical-layer security, reconfigurable intelligent surface (RIS) has been suggested to assist artificial noise (AN) to bridge both their advantages in multiple-input single-output (MISO) systems. Specifically, for achieving the trade-off between the reliability and security of transmission, the phase shifts (PSs) and beamforming are jointly designed based on the oblique manifold (OM) algorithm (Wang et al., 2020) without eavesdropper's channel state information (CSI). In order to alleviate the computational complexity, a novel alternating direction (AD) algorithm is proposed in this contribution. Specifically, the initial problem is transformed into several subproblems, each of which determines a specific RIS unit via a closed-form solution when the other configurations are fixed. Furthermore, the AD algorithm is investigated to exhibit the low-complexity advantage in contrast to OM. Simulation results illustrate that AD can converge faster and more stably compared to OM with the same performance.
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| 3. |
- Xiao, Sen, et al.
(författare)
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The influence of impact speed on chest injury outcome in whole body frontal sled impacts
- 2020
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Ingår i: Transport. - : Vilnius Gediminas Technical University. - 1648-4142 .- 1648-3480. ; 35:6, s. 669-678
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Tidskriftsartikel (refereegranskat)abstract
- While the seatbelt restraint has significantly improved occupant safety, the protection efficiency still needs further enhance to reduce the consequence of the crash. Influence of seatbelt restraint loading on chest injury under 40 km/h has been tested and documented. However, a comprehensive profiling of the efficiency of restraint systems with various impact speeds has not yet been sufficiently reported. The purpose of this study is to analyse the effect of the seatbelt load-ings on chest injuries at different impact speeds utilizing a high bio-fidelity human body Finite Element (FE) model. Based on the whole-body frontal sled test configuration, the current simulation is setup using a substitute of Post-Mortem Human Subjects (PMHS). Chest injury outcomes from simulations are analysed in terms of design variables, such as seatbelt position parameters and collision speed in a full factorial experimental design. These outcomes are specifically referred to strain-based injury probabilities and four-point chest deflections caused by the change of the parameters. The results indicate that impact speed does influence chest injury outcome. The ribcage injury risk for more than 3 fractured ribs will increase from around 40 to nearly 100% when the impact speed change from 20 to 40 km/h if the seatbelt positioned at the middle-sternum of this study. Great injuries to the chest are mainly caused by the change of inertia, which indicates that chest injuries are greatly affected by the impact speed. Furthermore, the rib fracture risk and chest deflection are nonlin-early correlated with the change of the seatbelt position parameters. The study approach can serve as a reference for seatbelt virtual design. Meanwhile, it also provides basis for the research of chest injury mechanism.
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| 4. |
- Yang, Ping, et al.
(författare)
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6G Wireless Communications: Vision and Potential Techniques
- 2019
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Ingår i: IEEE Network. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-156X .- 0890-8044. ; 33:4, s. 70-75
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Tidskriftsartikel (refereegranskat)abstract
- With the fast development of smart terminals and emerging new applications (e.g., real-time and interactive services), wireless data traffic has drastically increased, and current cellular networks (even the forthcoming 5G) cannot completely match the quickly rising technical requirements. To meet the coming challenges, the sixth generation (6G) mobile network is expected to cast the high technical standard of new spectrum and energy-efficient transmission techniques. In this article, we sketch the potential requirements and present an overview of the latest research on the promising techniques evolving to 6G, which have recently attracted considerable attention. Moreover, we outline a number of key technical challenges as well as the potential solutions associated with 6G, including physical-layer transmission techniques, network designs, security approaches, and testbed developments.
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| 5. |
- Xiao, Sen, et al.
(författare)
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Analysis of chest injury in frontal impact via finite element modelling based on biomechanical experiment
- 2017
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Ingår i: Lixue Xuebao/Chinese Journal of Theoretical and Applied Mechanics. - 0459-1879. ; 49:1, s. 191-201
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Tidskriftsartikel (refereegranskat)abstract
- The usage of the seatbelt as a part of the vehicle protection system has immensely promoted occupant safety. However, recent accident investigation shows that it is necessary to increase the chest injury protective e_ciency in frontal impact condition. This study aims to investigate the influence of seatbelt system design variables on occupant chest injury related physical parameters at varying impact conditions, especially concerning with the chest deflection and distribution of rib stress/strain. The study is conducted by using human body FE model in combination with post mortem human subjects tests. An FE model of the belted occupant is therefore established by using a baseline human body FE model (GHBMC), which is validated according to detailed experimental data regarding kinematics, seatbelt force and chest deflection. A parameter study is implemented in terms of seatbelt position, seatbelt angle and impact speed to determine the influence of seatbelt utilization on occupant thoracic injury in frontal impact. The results show that the influence of seatbelt position on chest deflection and distribution of rib stress/strain is greater than that of the seatbelt angle. Meanwhile, the trends of chest deflections are the same with the trends of the rib stress/strain responses while the changes of seatbelt design variables. This study provides a virtual test method on investigation of the chest injury biomechanics related to the seatbelt design variables. Furthermore, the results from this study of chest injury mechanism will also provide a reference for optimizing of the occupant restraint system. © 2017, Editorial Office of Chinese Journal of Theoretical and Applied Mechanics. All right reserved.
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| 6. |
- Xiao, Sen, et al.
(författare)
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Effect of contact friction between seatbelt and human body model on simulation of rib fracture in frontal impact
- 2016
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Ingår i: Proceedings - 2016 8th International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2016; Macau; China; 11 March 2016 through 12 March 2016. - 2157-1473. - 9781509023127 ; 9 June 2016, s. 255-257
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Konferensbidrag (refereegranskat)abstract
- Seatbelt contact friction coefficient may have some influence on chest injury prediction because it can affect the position of the seatbelt during the impact. The objective was to study the influence of the seatbelt contact friction coefficient on predicted rib fracture outcome in frontal impact. Four simulations of frontal impact sled tests in the same environment were conducted wherein the contact friction coefficient between the seatbelt and the chest model was varied. A noticeable effect was observed wherein increasing friction coefficient which tended to cause a slight decrease in the number of predicted fractures. Despite this, the magnitude of sensitivity was small, suggesting that in the absence of other information arbitrary values of friction coefficient within a reasonable intermediate range may be justified for this specific test condition.
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| 7. |
- Qian, Liangxin, et al.
(författare)
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Multi-Dimensional Polarized Modulation for Land Mobile Satellite Communications
- 2021
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Ingår i: IEEE Transactions on Cognitive Communications and Networking. - : Institute of Electrical and Electronics Engineers (IEEE). - 2332-7731. ; 7:2, s. 383-397
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Tidskriftsartikel (refereegranskat)abstract
- In this article, a novel multiple-input multiple-out (MIMO) transmission scheme, called generalized polarized enhanced spatial modulation (GPESM), is proposed for dual-polarized land mobile satellite (LMS) communications. We first introduce the enhanced spatial modulation (ESM) technique for dual-polarized LMS communications, in which polarization dimension, spatial dimension and multiple signal constellations are used to transmit information and obtain substantial performance gain. Meanwhile, the theoretical upper bound for the average bit error probability (ABEP) of the proposed GPESM scheme is derived. In order to further improve the reliability of the system, we also propose two novel power allocation (PA) algorithms for GPESM system, which are the optimization-driven approximated max-min distance (AMMD)-based PA algorithm and the data-driven deep neural network (DNN)-based PA algorithm. To achieve an enhanced spatial diversity gain, we consider to apply a reconfigurable intelligent surface (RIS) to the GPESM system as a relay to assist in transmitting information. In this way, the user can receive the information transmitted by the satellite on one hand, and the information sent by the satellite via the RIS relay on the other hand. We also extend the above-mentioned two PA algorithms to the RIS-assisted GPESM systems. Our simulation results show that the RIS-assisted GPESM systems are capable of obtaining high bit error rate (BER) performance gain (up to 10 dB) compared to the standard GPESM system and two PA algorithms can further improve the performance to the systems.
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| 8. |
- Tang, Jinfeng, 1984, et al.
(författare)
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Optimizing critical metals recovery and correlative decontamination from MSWI fly ash: Evaluation of an integrating two-step leaching hydrometallurgical process
- 2022
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526. ; 368
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Tidskriftsartikel (refereegranskat)abstract
- While municipal solid waste incineration (MSWI) fly ash is classified as hazardous waste, it can also serve as an urban mining source for numerous precious metals. Of particular interest are antimony (Sb) and zinc (Zn); the former of which is a strategic and critical metal that is being rapidly depleted, putting society at high risk for supply shortages. In this work, a two-step leaching method for recovering Sb and Zn from MSWI fly ash is proposed. Furthermore, the leaching behavior and adsorption mechanism of Sb in the MSWI fly ash waste stream were also investigated. Results from the first constant pH leaching tests (CPLT) showed that under diluted acidic condition, the maximum amount of Sb released from fly ash was ∼20%. In addition, at pH 4.0, 67% of the fly ash was dissolved, while 79.3% and 12.1% of the Zn and Sb, respectively, were recovered. After optimizing and executing a second Sb leaching procedure (6 M HCl solution at 60 °C), >80% of the Sb was recovered. Thus, the proposed two-step leaching process, consisting of extraction followed by decontamination using a magnetic HAP@CoFe2O4 adsorbent, can eliminate the Sb in fly ash effluent with a removal efficiency >95%. Moreover, this process produces less toxic products and lowers the effluent residue concentration. As such, the two-step process described herein is suggested for Sb and Zn recovery from fly ash; as it not only enables precious metal recovery, but also aids in treating secondary waste streams produced from urban mining.
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| 9. |
- Tang, Jinfeng, 1984, et al.
(författare)
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Source analysis of municipal solid waste in a mega-city (Guangzhou): Challenges or opportunities?
- 2018
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Ingår i: Waste Management and Research. - 1096-3669 .- 0734-242X. ; 36:12, s. 1166-1176
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Tidskriftsartikel (refereegranskat)abstract
- Rapid economic development accelerates the generation of municipal solid waste (MSW), and thereby calls for an effective and reliable waste management strategy. In the present work, we systematically investigated the status of MSW management in a mega-city of China (Guangzhou). The data were collected from literatures, government statistics and field sampling work. It can be found that a combination of waste sorting by individual residents and a necessary quantity of sanitation workers is one of the most feasible strategies to achieve a sustainable waste management. With implementation of that integrated strategy, approximately 0.03 million tons of metal, 0.24 million tons of paper, as well as 0.46 million tons of plastics can be recycled/recovered for further processing. A cost reduction of 70 million US$ is achieved in comparison with the un-optimized system due to the sale revenue of recyclable materials and the saving from waste disposal fees. The values of environmental assessment were expressed as environmental load units. The developed scenarios could decrease the environmental cost, namely, 0.66 million US$. Based on the studies, waste sorting is urgently needed in Guangzhou. However, to make the proposed strategy to be more economically feasible, the sorting should be performed individually as well as with public participation. The establishment of a win–win situation for all stakeholders is an effective path for the improvement of the integrated waste management system.
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| 10. |
- Wu, Mingming, et al.
(författare)
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Design of Reconfigurable Intelligent Surface-Aided Cross-Media Communications
- 2022
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Ingår i: IEEE Transactions on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0090-6778 .- 1558-0857. ; 70:12, s. 8433-8447
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Tidskriftsartikel (refereegranskat)abstract
- A novel reconfigurable intelligent surface (RIS)-aided hybrid reflection/transmitter design is proposed for achieving information exchange in cross-media communications. In pursuit of the balance between energy efficiency and low-cost implementations, the cloud-management transmission protocol is adopted in the integrated multi-media system. Specifically, the messages of devices using heterogeneous propagation media, are firstly transmitted to the medium-matched AP, with the aid of the RIS-based dual-hop transmission. After the operation of intermediate frequency conversion, the access point (AP) uploads the received signals to the cloud for further demodulating and decoding process. Based on time division multiple access (TDMA), the cloud is able to distinguish the downlink data transmitted to different devices and transforms them into the input of the RIS controller via the dedicated control channel. Thereby, the RIS can passively reflect the incident carrier back into the original receiver with the exchanged information during the preallocated slots, following the idea of an index modulation-based transmitter. Moreover, the iterative optimization algorithm is utilized for optimizing the RIS phase, transmit rate and time allocation jointly in the delay-constrained cross-media communication model. Our simulation results demonstrate that the proposed RIS-based scheme can improve the end-to-end throughput than that of the AP-based transmission, the equal time allocation, the random and the discrete phase adjustment benchmarks.
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